Unravelling the structural plasticity of stretched DNA under torsional constraint
Unravelling the structural plasticity of stretched DNA under torsional constraint
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DOI：
10.1038/ncomms11810
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发表时间：
2016-06-01
影响因子：
16.6
通讯作者：
Wuite, Gijs J. L.
中科院分区：
文献类型：
--
作者：
King, Graeme A.;Peterman, Erwin J. G.;Wuite, Gijs J. L.
基因组的某些区域经常受到扭转的限制。然而，这种限制对基因组代谢过程中DNA-蛋白质相互作用的影响仍然知之甚少。在这里，使用组合的光镊和荧光显微镜，我们量化和解释扭转约束如何影响DNA的结构稳定性下施加的张力。我们提供了直接的证据，伴随碱基对熔化和螺旋解旋可以发生在扭转约束的DNA在力>类似于50 pN。这个惊人的结果表明，连接数的局部变化可以被DNA双链体的其余部分吸收。我们还提出了令人信服的新证据，即在>类似于110 pN的力下，产生了过度缠绕的DNA结构（可能是P-DNA）（与下缠绕结构一起）。这些发现证实了以前的理论预测，并强调了一个显着的结构可塑性的扭转约束DNA。这种可塑性可能需要在体内吸收的扭转约束下举行的DNA中的连接数的局部变化。
Regions of the genome are often held under torsional constraint. Nevertheless, the influence of such constraint on DNA-protein interactions during genome metabolism is still poorly understood. Here using a combined optical tweezers and fluorescence microscope, we quantify and explain how torsional constraint influences the structural stability of DNA under applied tension. We provide direct evidence that concomitant basepair melting and helical unwinding can occur in torsionally constrained DNA at forces > similar to 50 pN. This striking result indicates that local changes in linking number can be absorbed by the rest of the DNA duplex. We also present compelling new evidence that an overwound DNA structure (likely P-DNA) is created (alongside underwound structures) at forces > similar to 110 pN. These findings substantiate previous theoretical predictions and highlight a remarkable structural plasticity of torsionally constrained DNA. Such plasticity may be required in vivo to absorb local changes in linking number in DNA held under torsional constraint.